Covering material for smoking products having improved carbon monoxide reducing properties

ABSTRACT

The smoking article wrapping material contains calcium carbonates of differing particle size as a filler, one of the calcium carbonates having a particle size in the range from 0.1 to 2 μm and being present in an amount of 51-99%, based on the total content of calcium carbonate fillers, and another calcium carbonate having a particle size of 3.5-10 μm and being present in an amount of 1-49%, based on the total content of calcium carbonate fillers.

The present invention relates to an improved smoking article wrapping material which reduces the carbon monoxide delivery as a constituent of the smoke components from smoking articles, such as cigarettes, without the air permeability of the smoking article wrapping paper in the unburned state being altered.

It is known in the pertinent field that reduced delivery of carbon monoxide (CO) as a constituent of the smoke ingredients can be achieved by increasing the air permeability of the smoking article wrapping paper or by altering the proportion of organic substances (cellulose for example) and inorganic substances (for example filler, preferably calcium carbonate) in the smoking article wrapping material (cf. for example CA-A-2065788) or by reducing the mass of the smoking article wrapping material (cf. for example WO-A-03/034846) or by using catalysts.

Existing inventions and applications directly or indirectly seek to have the air permeability of the smoking article wrapping material altered, which in but minimally altered conditions reduces all the smoke ingredients and alters the puff count of a smoking article.

Frequently, however, these solutions only succeed in bringing about a slight reduction in the carbon monoxide content or the ratio of the smoke ingredients, in particular the ratio of CO to dry tar taken into account by legislation, is only insignificantly affected.

Furthermore, prior art catalysts for reducing CO affect the appearance of the smoking article wrapping papers or do not conform to legislation.

It is an object of the present invention to overcome the above problems and provide a smoking article wrapping material which provides a reduction in the carbon monoxide content of the smoke ingredients without its air permeability being altered.

We have found that this object is achieved, surprisingly, by a smoking article wrapping material containing as a filler two calcium carbonates differing in particle size and amount.

The present invention accordingly provides in one aspect a smoking article wrapping material containing calcium carbonates of differing particle size as a filler, one of the calcium carbonates having a particle size in the range from 0.1 to 2 μm and being present in an amount of 51-99%, based on the total content of calcium carbonate fillers, and another calcium carbonate having a particle size of 3.5 to 10 μm and being present in an amount of 1-49%, based on the total content of calcium carbonate fillers.

In a preferred embodiment of the present invention, the smoking article wrapping material of the present invention is a cigarette paper.

In another preferred embodiment of the present invention, the total filler content of the smoking article wrapping material of the present invention is 10 to 50%, preferably in the range from 25% to 40%, based on the total weight of the smoking article wrapping material.

The calcium carbonates used according to the present invention comprise a calcium carbonate in a particle size ranging from 0.1 to 2.0 μm and preferably from 0.3 to 1 μm, this calcium carbonate being present in an amount of 51-99% and preferably 70-95%, based on the total amount of the fillers, and also a second calcium carbonate in a particle size of 3.5 to 10 μm and preferably in the range from 4 to 6 μm, this second calcium carbonate being present in an amount of 1-49% and preferably 5-30%, based on the total amount of the fillers.

The smoking article wrapping material of the present invention may optionally have added to it further fillers such as calcium carbonate in another particle size, titanium dioxide, magnesium oxide, talc or kaolin.

Differentiating the particle size of the calcium carbonates is operative in the combustion of the smoking article wrapping material combined with a smoking article, preferably a cigarette, fabricated therefrom, in forming an outer tube of ash having a particular kind of porous structure.

The porous structure of the burned smoking article wrapping paper is determined essentially by the present invention's combination of two calcium carbonates differing in particle size and amount and the total amount of calcium carbonate and only insignificantly by the level of the smoking article wrapping material's air permeability.

The smoking article wrapping material of the present invention may optionally contain a burn rate retarder and/or a burn rate enhancer.

In accordance with the present invention, disodium hydrogenphosphate is a suitable burn rate retarder.

Useful burn rate enhancers include according to the present invention alkali metal or alkaline earth metal salts, such as salts of sodium, of potassium and of magnesium, or carboxylate salts, such as acetate, citrate, malate, lactate and tartrate salts, in particular citrate salts.

The fractions of the respective constituents in the smoking article wrapping material of the present invention are typically, if present, 0-6% and preferably 0-3% of burn rate retarder and/or enhancer, based in each case on the total weight of the smoking article wrapping material.

The base wrapping material to be used according to the present invention for the smoking article wrapping material consists typically of cellulose fibers obtained from flax, softwood or hardwood for example. To alter the properties of the base wrapping material if desired, various mixtures of cellulose fibers can be used as base wrapping material.

The basis weight of the smoking article wrapping material used according to the present invention is typically in the range from 15 to 60 g/m² and preferably in the range from 18 to 40 g/m².

The present invention further provides a method of reducing the carbon monoxide fraction in the smoke from a smoking article, which comprises incorporating in a smoking article wrapping material while preserving the air permeability of the smoking article wrapping material calcium carbonate fillers of differing particle size in a suitable mixing ratio, one of the calcium carbonates having a particle size in the range from 0.1 to 2 μm and being incorporated in an amount of 51 to 99%, based on the total content of calcium carbonate fillers, and another calcium carbonate having a particle size in the range from 3.5 to 10 μm and being incorporated in an amount of 1 to 49%, based on the total content of calcium carbonate fillers.

The inventors found that, surprisingly, suitable incorporation of the abovementioned calcium carbonate fillers in a suitable mixing ratio preserves the air permeability of the smoking article wrapping material. At the same time, however, the present invention's incorporation of the calcium carbonate fillers mentioned surprisingly reduces the fraction of carbon monoxide in the smoke and also, advantageously and desirably, the ratio of carbon monoxide to dry tar.

The present invention further provides a smoking article comprising a tobacco rod, a smoking article wrapping material whose filler contains two calcium carbonates differing in particle size and amount, one calcium carbonate having a particle size of 0.1-2 μm and being present in a 51-99% fraction and the other having a particle size of 3.5-10 μm and being present in a 1-49% fraction, and if appropriate a filter.

The particle size of the calcium carbonates used according to the present invention was determined by means of a sedigraph.

The present invention further provides a method of reducing the carbon monoxide content of smoke ingredients in a smoking article comprising a tobacco rod, a smoking article wrapping material and if appropriate a filter, which comprises incorporating in a smoking article wrapping material calcium carbonate fillers of differing particle size, one of the calcium carbonates having a particle size in the range from 0.1 to 2 μm and being incorporated in an amount of 51-99%, based on the total content of calcium carbonate fillers, and another calcium carbonate having a particle size of 3.5-10 μm and being incorporated in an amount of 1-49%, based on the total content of calcium carbonate fillers.

EXAMPLE 1

Cig1a 60 cigarette paper comprising a burn control additive (burn control additive: sodium acetate, air permeability 60 CU, 33% filler content, 25 g/m², Julius Glatz GmbH, Neidenfels) was produced. The filler was made up of 80% of Precarb 720 (average particle size 0.5 μm as per sedigraph measurement, Schaefer Kalk, Dietz) and 20% of Precarb 160 G (average particle size 4.2 μm as per sedigraph measurement, Schaefer Kalk, Dietz).

Test cigarettes utilizing the above cigarette paper as wrapping material were produced to the following features:

diameter 7.8 mm, total length 84 mm, rod length 59 mm, total drawing resistance 129 mm hydrohead.

The smoke ingredients found were:

carbon monoxide 6.7 mg/cig dry tar 6.6 mg/cig carbon monoxide/dry tar 1.02

EXAMPLE 2

Cigla 60 cigarette paper comprising a burn control additive (burn control additive: potassium citrate, air permeability 60 CU, 29% filler content, 25 g/m², Julius Glatz GmbH, Neidenfels) was produced. The filler was made up of 80% of Precarb 720 (average particle size 0.5 μm as per sedigraph measurement, Schaefer Kalk, Dietz) and 20% of Precarb 160 G (average particle size 4.2 μm as per sedigraph measurement, Schaefer Kalk, Dietz).

Test cigarettes utilizing the above cigarette paper as wrapping material were produced to the following features:

diameter 7.8 mm, total length 84 mm, rod length 59 mm, total drawing resistance 130 mm hydrohead.

The smoke ingredients found were:

carbon monoxide 6.6 mg/cig dry tar 6.3 mg/cig carbon monoxide/dry tar 1.05

COMPARATIVE EXAMPLE

Cigla 60 cigarette paper comprising a burn control additive (burn control additive: sodium acetate, air permeability 60 CU, 33% filler content, 25 g/m², Julius Glatz GmbH, Neidenfels) was produced. The filler was made up of 100% of Precarb 122VP (average particle size 1.6 μm as per sedigraph measurement, Schaefer Kalk, Dietz).

Test cigarettes utilizing the above cigarette paper as wrapping material were produced to the following features:

diameter 7.8 mm, total length 84 mm, rod length 59 mm, total drawing resistance 129 mm hydrohead.

The smoke ingredients found were:

carbon monoxide 8.2 mg/cig dry tar 7.0 mg/cig carbon monoxide/dry tar 1.17

While air permeability was unaltered and further features of the cigarette paper were identical between Examples 1 and 2 and comparative example on the one hand and identical test cigarette construction on the other, the carbon monoxide content in the smoke from the specimens according to the present invention was reduced by more than 15% and, furthermore, the ratio of carbon monoxide to dry tar was changed in an advantageous direction. 

1-8. (canceled)
 9. A smoking article wrapping material comprising calcium carbonates of differing particle size as a filler, a first of the calcium carbonates having a particle size in a range from 0.1 to 2 μm and being present in an amount of 51-99% based on a total content of the calcium carbonates, and a second of the calcium carbonates having a particle size of from 3.5-10 μm and being present in an amount of 1-49% based on the total content of the calcium carbonates.
 10. The smoking article wrapping material according to claim 9 comprising a cigarette paper.
 11. The smoking article wrapping material according to claim 9, wherein the first of the calcium carbonates has a particle size in a range from 0.3 to 1 μm and is present in an amount of 70-95% based on the total content of the calcium carbonates, and the second of the calcium carbonates has a particle size of 4-6 μm and is present in an amount of 5-30% based on the total content of said calcium carbonates.
 12. The smoking article wrapping material according to claim 10, wherein the first of the calcium carbonates has a particle size in a range from 0.3 to 1 μm and is present in an amount of 70-95% based on the total content of the calcium carbonates, and the second of the calcium carbonates has a particle size of 4-6 μm and is present in an amount of 5-30% based on the total content of said calcium carbonates.
 13. The smoking article wrapping material according to claim 9, wherein the total filler content is 10-50% based on the total weight of the smoking article wrapping material.
 14. The smoking article wrapping material according to claim 10, wherein the total filler content is 10-50% based on the total weight of the smoking article wrapping material.
 15. The smoking article wrapping material according to claim 13, wherein the total content of the calcium carbonates is from 25% to 40%.
 16. The smoking article wrapping material according to claim 9, further comprising at least one additional filler selected from the group consisting of calcium carbonate having a particle size different from said particle size of said first calcium carbonates and said second of the calcium carbonates, titanium dioxide, magnesium oxide, kaolin and/or talc.
 17. A method of reducing a carbon monoxide fraction in smoke from a smoking article, said method comprising incorporating in a smoking article wrapping material, while preserving air permeability of the smoking article wrapping material, calcium carbonate fillers of differing particle size in an operative mixing ratio, a first of the calcium carbonate fillers having a particle size in a range from 0.1 to 2 μm and being incorporated in an amount of 51 to 99% based on a total content of the calcium carbonate fillers, and a second of said calcium carbonate fillers having a particle size in a range from 3.5 to 10 μm and being incorporated in an amount of 1 to 49% based on the total content of the calcium carbonate fillers.
 18. A smoking article comprising a tobacco rod, a smoking article wrapping material according to claim 9, 10, 11, 12, 13, 14, 15 or 16 and, optionally, a filter. 